Large-scale excavation of the earth's surface may be carried out with what is commonly called a "dragline" machine. This machine basically employs a large boom, in the order of 240 feet, to lower an excavation bucket by means of a lift cable to a desired point on the earth where excavating is to be done. This bucket has teeth which dig into the earth for removing dirt as the bucket is reeled in or dragged by means of a pull cable extending along the earth's surface to the bucket. Such a dragline, as one manufactured by Page Engineering, weighs up to four million pounds and can dig at a rate of up to 2,640 cubic yards an hour. Run by a two-person crew, an operator and an oiler, the dragline machine uses electric current supplied by a cable from a power substation. Other dragline manufacturers are Bucyrus-Erie Company, Milwaukee, Wis.; American Hoist & Derrick Co., St. Paul, Minn.; and Manitowoc Engineering Co., Manitowoc, Wis.